In the past, many different types of magnetic tape data memories have been devised or proposed, and at an earlier point in time such devices constituted the most widely used long-term storage medium for large quantities of data. A very frequently-encountered form of such a tape memory, used with large main-frame computers, utilizes relatively wide tape (on the order of one-half inch) which is used with large, open reels, in a reel-to-reel configuration.
With the increasingly widespread development and use of smaller types of data processing and/or word processing equipment, involving "stand-alone" desk-top processor devices comparable in physical size to the input terminals used in larger computer installations, there has been an increasing emphasis on the development of smaller forms of data storage devices. Thus, a significant advent in the development of "stand-alone" terminals (U.S. Pat. No. 3,760,375) utilized tape cassettes of the nature typically used in audio equipment, embodying eighth-inch tape. Following that, the "floppy" disc ("diskette") was developed and has now come into widespread usage, particularly in office-type or business computer applications. Also, many developments have taken place in "hard" disc drives and memory units to make them suitable for such use, e.g., development of "Winchester"-type drives.
In this increasing development, the two major underlying purposes are the need to obtain increased amounts of storage without corresponding increase in physical size, as well as the need to actually reduce the size of both the storage media and of the drive which utilizes the same. Thus, "floppy" disc media and drives have become available in sizes on the order of one-half that of the initial such devices, and the same is certainly true of "hard" disc drives, in which the media diameter has been reduced to approximately five and one-quarter inches (for "mini" disc drives) and to on the order of three and three-quarter inches (and indeed, in some instances, three inches) in more recent units (often known as "micro" disc drives).
Accordingly, there is an increasing need for analogous developments in tape storage media and drives, particularly for longer-term storage, inasmuch as high storage capacities may be achieved at relatively low cost by the use of tape media, and the use of tape as a storage media lends itself very admirably to "backup" or "archive" storage for the disc memories used as working or operating storage during entry or processing operations.